How to kill/terminate running e4defrag without damaging my data?

If I kill a running e4defrag , is there a risk of data loss/corruption? Is there a safe way to interrupt it? For example: running e4defrag on large partition (such as the root directory) or large file (such as a squashfs system image file) is very slow, so sometimes, stopping/killing e4defrag before it is done is needed, but I'm not sure whether killing it (by sending either of SIGINT,SIGTERM,SIGKILL, etc. to it) e4defrag is safe? I'm running Debian Stretch and the filesystem is ext4. My kernel version:4.14.13 My e2fsprogs version:1.43.4-2